What is the Cause of Biotrickling Filters Blockage?

Question

We are using biotrickling filters to remove hydrogen sulphide gas (H2S) from waste water. 
The differential pressure inside the cylinders indicates that the media inside is blocked. The problem remained even after flushing. 
What could be the reason for the blocked cylinders? How do we solve the blockage and how do we prevent it from happening again?

Prem Baboo · Answer

Dear Zyaad Aboud,
High rate and roughing filters, increased hydraulic loading is required to flush the sloughed material through the filter and avoid anaerobic conditions as a result of filter clogging. Realistically clogging is only likely for rock media filters and / or where screening is not applied as part of pre-treatment phasehigh protein content of the wastewater led to heavy biological growth resulting in clogging.

Marina Vasiljevic · Answer

It would be good to know what package is used in bio trickling filter as well as is it operating full capacity.
I have found some suggestions from Lantec company  based on results of their  pilot plant (with patented media) for wastewater pumping station in USA 
here is the chapter
"When the biofilter was started up in May 1999, the H2S removal efficiency increased gradually as biofilm developed on the media, but it remained below 45%. A commercial lawn-fertilizer dispenser was connected to the make-up water line to add ammonium phosphate and urea as micronutrients. After that, the H2S removal efficiency rose to over 90% within a few days. Since then, the removal has been consistently over 90%, even though the inlet H2S level varied as much as 400% within the same day"
the link is here
http://www.lantecp.com/products/hd-q-pac/biotricklingarticle
Looking forward receiving more data on your biotrickling filter media

Jeremy Biddle · Answer

It is likely that you have got elemental sulphur deposited in your scrubber, due to incomplete oxidation of the hydrogen sulphide. Instead of forming sulphate, it stops at solid sulphur (yellow colour) and its not easy to get rid of once it has formed. Best to replace the media if you can.
If this is indeed the cause of the blockage, the reason it has formed will probably be that the pH of the scrubber is too low (acidic/neutral). H2S scrubbers should operate at pH > 9.

Antonio Bowers · Answer

Is the media that you are actually using plastic cylinders?

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